Targeting foamy macrophages by manipulating ABCA1 expression to facilitate lesion healing in the injured spinal cord.

Spinal cord injury (SCI) triggers a complex cascade of events, including myelin loss, neuronal damage, neuroinflammation, and the accumulation of damaged cells and debris at the injury site. Infiltrating bone marrow derived macrophages (BMDMϕ) migrate to the epicenter of the SCI lesion, where they engulf cell debris including abundant myelin debris to become pro-inflammatory foamy macrophages (foamy Mϕ), participate neuroinflammation, and facilitate the progression of SCI. This study aimed to elucidate the cellular and molecular mechanisms underlying the functional changes in foamy Mϕ and their potential implications for SCI. Contusion at T10 level of the spinal cord was induced using a New York University (NYU) impactor (5 g rod from a height of 6.25 mm) in male mice. ABCA1, an ATP-binding cassette transporter expressed by Mϕ, plays a crucial role in lipid efflux from foamy cells. We observed that foamy Mϕ lacking ABCA1 exhibited increased lipid accumulation and a higher presence of lipid-accumulated foamy Mϕ as well as elevated pro-inflammatory response in vitro and in injured spinal cord. We also found that both genetic and pharmacological enhancement of ABCA1 expression accelerated lipid efflux from foamy Mϕ, reduced lipid accumulation and inhibited the pro-inflammatory response of foamy Mϕ, and accelerated clearance of cell debris and necrotic cells, which resulted in functional recovery. Our study highlights the importance of understanding the pathologic role of foamy Mϕ in SCI progression and the potential of ABCA1 as a therapeutic target for modulating the inflammatory response, promoting lipid metabolism, and facilitating functional recovery in SCI.

Chaperone-mediated autophagy (CMA) alleviates cognitive impairment by reducing neuronal death in sepsis-associated encephalopathy (SAE).

Sepsis-associated encephalopathy (SAE) is a common and severe complication of sepsis, which causes long-term neurological deficits, such as cognitive impairment. Despite extensive research, there is still lack of specific treatments for SAE. Chaperone-mediated autophagy (CMA), a selective type of autophagy, has been reported to be related to cognitive dysfunctions in many neurodegenerative diseases. The aim of this study was to investigate the alteration of CMA activity in the hippocampus of SAE mice and explore the neuroprotective effect of enhanced CMA. Cecal ligation and puncture (CLP) was conducted to induce SAE. In the contextual fear conditioning test, the ratio of freezing time of CLP mice significantly decreased compared with that of the mice in the Sham group, indicating cognitive impairment in SAE mice. The expression of lysosome-associated membrane protein type 2A (Lamp2a) and chaperone heat shock cognate 71 kDa protein (Hsc70), positive markers for CMA activity, decreased in hippocampal neurons of SAE mice. Although overexpression of Lamp2a in neurons via adeno-associated virus injection in the hippocampus had little effect on the mortality of septic mice, this intervention significantly alleviated the memory impairments in contextual fear conditioning test, Y-maze test and novel objective recognition test, and attenuated the neural death observed in SAE mice. We further demonstrated that the overexpression of Lamp2a in the hippocampus increased the expression of phosphorylated cyclic-AMP response element binding protein (p-CREB), brain-derived neurotrophic factor (BDNF) and B-cell lymphoma-2 (Bcl-2), and suppressed the expression of cleaved caspase-3. Taken together, our study results suggested that the upregulation of CMA activity ameliorated cognitive impairments and neuron loss in SAE mice partially through the p-CREB-BDNF/Bcl-2 signaling pathways, providing a potential therapeutic target for SAE.

Hydralazine plays an immunomodulation role of pro-regeneration in a mouse model of spinal cord injury.

Spinal cord injury (SCI) results in severe motor and sensory dysfunction with no effective therapy. Spinal cord debris (sp) from injured spinal cord evokes secondary SCI continuously. We and other researchers have previously clarified that it is mainly bone marrow derived macrophages (BMDMs) infiltrating in the lesion epicenter to clear sp, rather than local microglia. Unfortunately, the pro-inflammatory phenotype of these infiltrating BMDMs is predominant which impairs wound healing. Hydralazine, as a potent vasodilator and scavenger of acrolein, has protective effects in many diseases. Hydralazine is also confirmed to promote motor function and hypersensitivity in SCI rats through scavenging acrolein. However, few studies have explored the effects of hydralazine on immunomodulation, as well as spontaneous pain and emotional response, the important syndromes in clinical patients. It remains unclear whether hydralazine affects infiltrating BMDMs after SCI. In this study, we targeted BMDMs to explore the influence of hydralazine on immune cells in a mouse model of SCI, and also investigated the contribution of polarized BMDMs to hydralazine-induced neurological function recovery after SCI in male mice. The adult male mice underwent T10 spinal cord compression. The results showed that in addition to improving motor function and hypersensitivity, hydralazine relieved SCI-induced spontaneous pain and emotional response, which is a newly discovered function of hydralazine. Hydralazine inhibited the recruitments of pro-inflammatory BMDMs and educated infiltrated BMDMs to a more reparative phenotype involving in multiple biological processes associated with SCI pathology, including immune/inflammation response, neurogenesis, lipid metabolism, oxidative stress, fibrosis formation, and angiogenesis, etc. As an overall effect, hydralazine-treated BMDMs loaden with sp partially rescued neurological function after SCI. It is concluded that hydralazine plays an immunomodulation role of educating pro-inflammatory BMDMs to a more reparative phenotype; and hydralazine-educated BMDMs contribute to hydralazine-induced improvement of neurological function in SCI mice, which provides support for drug and cell treatment options for SCI therapy.

Selective activation of cholinergic neurotransmission from the medial septal nucleus to hippocampal pyramidal neurones improves sepsis-induced cognitive deficits in mice.

BACKGROUND: Sepsis-associated encephalopathy is characterised by cognitive dysfunction, and might be mediated by deficits in neurotransmission. Reduced cholinergic neurotransmission in the hippocampus impairs memory function. We assessed real-time alterations of acetylcholine neurotransmission from the medial septal nucleus to the hippocampus, and explored whether sepsis-induced cognitive deficits can be relieved by activating upstream cholinergic projections. METHOD: Lipopolysaccharide (LPS) injection or caecal ligation and puncture (CLP) was used to induce sepsis and associated neuroinflammation in wild-type and mutant mice. Adeno-associated viruses for calcium and acetylcholine imaging, and for optogenetic and chemogenetic modulation of cholinergic neurones were injected into the hippocampus or medial septum, and a 200-µm-diameter optical fibre was implanted to collect acetylcholine and calcium signals. Cholinergic activity of the medial septum was manipulated and combined with cognitive assessment after LPS injection or CLP. RESULTS: Intracerebroventricular LPS injection reduced postsynaptic acetylcholine (from 0.146 [0.001] to 0.0047 [0.0005]; p=0.004) and calcium (from 0.0236 [0.0075] to 0.0054 [0.0026]; p=0.0388) signals in hippocampal Vglut2-positive glutamatergic neurones, whereas optogenetic activation of cholinergic neurones in the medial septum reversed LPS-induced reductions in these two signals. Intraperitoneal LPS injection decreased acetylcholine concentration in the hippocampus (476 [20] pg ml-1 to 382 [14] pg ml-1; p=0.0001). Reduction in long-term potentiation (238 [23] % to 150 [12] %; p=0.0082) and enhancement of hippocampal pyramidal neurone action potential frequency (5.8 [1.5] Hz to 8.2 [1.8] Hz; p=0.0343) were relieved, and neurocognitive performance was improved by chemogenetic activation of cholinergic innervation of the hippocampus 3 days after LPS injection in septic mice. CONCLUSIONS: Systemic or local LPS reduced cholinergic neurotransmission from the medial septum to hippocampal pyramidal neurones, and their selective activation alleviated defects in hippocampal neuronal function and synaptic plasticity and ameliorated memory deficits in sepsis model mice through enhanced cholinergic neurotransmission. This provides a basis for targeting cholinergic signalling to the hippocampus in sepsis-induced encephalopathy.

An MD2-perturbing peptide has therapeutic effects in rodent and rhesus monkey models of stroke.

Studies have failed to translate more than 1000 experimental treatments from bench to bedside, leaving stroke as the second leading cause of death in the world. Thrombolysis within 4.5 hours is the recommended therapy for stroke and cannot be performed until neuroimaging is used to distinguish ischemic stroke from hemorrhagic stroke. Therefore, finding a common and critical therapeutic target for both ischemic and hemorrhagic stroke is appealing. Here, we report that the expression of myeloid differentiation protein 2 (MD2), which is traditionally regarded to be expressed only in microglia in the normal brain, was markedly increased in cortical neurons after stroke. We synthesized a small peptide, Trans-trans-activating (Tat)-cold-inducible RNA binding protein (Tat-CIRP), which perturbed the function of MD2 and strongly protected neurons against excitotoxic injury in vitro. In addition, systemic administration of Tat-CIRP or genetic deletion of MD2 induced robust neuroprotection against ischemic and hemorrhagic stroke in mice. Tat-CIRP reduced the brain infarct volume and preserved neurological function in rhesus monkeys 30 days after ischemic stroke. Tat-CIRP efficiently crossed the blood-brain barrier and showed a wide therapeutic index for stroke because no toxicity was detected when high doses were administered to the mice. Furthermore, we demonstrated that MD2 elicited neuronal apoptosis and necroptosis via a TLR4-independent, Sam68-related cascade. In summary, Tat-CIRP provides robust neuroprotection against stroke in rodents and gyrencephalic nonhuman primates. Further efforts should be made to translate these findings to treat both ischemic and hemorrhagic stroke in patients.

Aspirin-Triggered Lipoxin Protects Lipopolysaccharide-Induced Acute Kidney Injury via the TLR4/MyD88/NF-κB Pathway.

The protective effect of aspirin-triggered lipoxin (ATL) on lipopolysaccharide (LPS)-induced acute kidney injury (AKI) and its possible mechanisms were explored. To induce acute renal injury, mice were treated with LPS. Concentration of serum creatinine (SCr) and blood urea nitrogen (BUN) was detected, and inflammatory cytokines and AKI biomarkers were determined by ELISA. The relative protein expression levels of TLR4/myeloid differentiation factor 88 (MyD88)/NF-κB signal pathway was assessed by Western blot. Mice subjected to LPS (4 mg/kg) treatment exhibited AKI demonstrated by markedly increased SCr and BUN levels compared with controls (P <0.01). Treatment with ATL decreased SCr and BUN levels after LPS injection (P <0.01). AKI biomarkers, such as urine NGAL, KIM-1, netrin-1, and L-FABP levels, increased by LPS and were inhibited by ATL (P <0.01). ATL also reduced LPS-induced secretion of inflammatory cytokines such as tumor necrosis factor-alpha, interleukin (IL)-1ß, IL-6, and IL-8 (P <0.01). Furthermore, mice pretreated with ATL before exposure to LPS showed a reduction in TLR, MyD88, and p65 phosphorylation (P <0.01), which are the key factors of the TLR/MyD88/NF-κB signaling pathway. These results indicated that ATL had protective effects on renal function and showed amelioration of LPS-induced kidney injury. The mechanisms underlying the protective effects of ATL can be considered are related to attenuation of the TLR4/MyD88/NF-κB signaling pathway.

Silencing miR-106b improves palmitic acid-induced mitochondrial dysfunction and insulin resistance in skeletal myocytes.

MicroRNA­106b (miR­106b) is reported to correlate closely with skeletal muscle insulin resistance. In the current study the effect of miR­106b on palmitic acid (PA)­induced mitochondrial dysfunction and insulin resistance was investigated in C2C12 myotubes via the silencing of miR­106b. MiR­106b expression was increased under PA treatment, while miR­106b loss of function improved insulin sensitivity by upregulating its target mitofusin­2 (Mfn2) in C2C12 myocytes. Furthermore, miR­106b loss of function partly improved mitochondrial morphological lesions and increased the levels of mitochondial DNA and intracellular adenosine triphosphate that had been impaired by PA exposure in C2C12 myocytes. MiR­106b loss of function attenuated the levels of intracellular reactive oxygen species (ROS), and upregulated the expression levels of the estrogen­related receptor (ERR)­α/peroxisome proliferative activated receptor γ coactivator (PGC)­1α/Mfn2 axis under PA exposure. In addition, miR­106b negatively regulated skeletal muscle mitochondrial function and insulin sensitivity under PA­induced insulin resistance by targeting Mfn2, which may be associated with reduced ROS and upregulation of the ERR­α/PGC­1α/Mfn2 axis.

MicroRNA-106b induces mitochondrial dysfunction and insulin resistance in C2C12 myotubes by targeting mitofusin-2.

MicroRNA-106b (miR-106b) is reported to correlate closely with skeletal muscle insulin resistance and type 2 diabetes. The aim of this study was to identify an mRNA targeted by miR-106b which regulates skeletal muscle insulin sensitivity. MiR-106b was found to target the 3' untranslated region (3' UTR) of mitofusin-2 (Mfn2) through miR-106b binding sites and to downregulate Mfn2 protein abundance at the post-transcriptional level by luciferase activity assay combined with mutational analysis and immunoblotting. Overexpression of miR-106b resulted in mitochondrial dysfunction and insulin resistance in C2C12 myotubes. MiR-106b was increased in insulin-resistant cultured C2C12 myotubes induced by TNF-α, and accompanied by increasing Mfn2 level, miR-106b loss of function improved mitochondrial function and insulin sensitivity impaired by TNF-α in C2C12 myotubes. In addition, both overexpression and downregulation of miR-106b upregulated peroxisome proliferator-activated receptor gamma coactivator (PGC)-1α and estrogen-related receptor (ERR)-α expression. MiR-106b targeted Mfn2 and regulated skeletal muscle mitochondrial function and insulin sensitivity. Therefor, Inhibition of miR-106b may be a potential new strategy for treating insulin resistance and type 2 diabetes.

[Cyclosporin A treatment of 83 children with nephrotic syndrome of different pathological types].

OBJECTIVE: To evaluate the efficacy of cyclosporin A (CyA) therapy in 83 children with nephrotic syndrome of different pathological types. METHODS: Eighty-three children enrolled in this study were all hospitalized children with idiopathic nephrotic syndrome, aged 3 to 14 yrs (average 8.3 yrs) and included 52 males and 31 females. There were 35 cases with steroid-dependent, 17 with steroid resistant and 26 with frequent relapses. CyA was given to each patient with dosage of 5 mg/(kg.d) during the corticosteroid was diminished. The renwal biopsy was performed in all patients before the administration of CyA. The duration of CyA therapy lasted for about 3 to 6 months. The plasma concentration of CyA was monitored. RESULTS: Eighty-three children with nephrotic syndrome of different pathological types were treated with CyA, including 42 cases of minimal change nephrotic syndrome (MCNS), 31 cases of mesangioproliferative glomerulonephritis (MsPGN), 5 cases of membranoproliferative glomerulonephritis (MPGN) and 4 cases of focal segmental glomerular sclerosis (FSGS). All the 83 patients tolerated well to the CyA treatment. Forty-five cases got complete remission, 23 partial remission, 15 cases no change after one month treatment with CyA in the hospital. The overall response rate was 82%. Patients with different renal pathological types showed different responses. Among them, MCNS and MsPGN exhibited the best response rates of 86% and 84%, respectively; MPGN cases showed a lower response rate and FSGS cases showed the lowest rate. The response time was 7 to 45 days. The blood concentration of CyA was monitored for 1 week and 2 weeks after the drug was given. The effective drug concentration was maintained at 100 to 200 microg/L, and the course lasted for 3 to 6 months. During the follow-up of 83 cases, in 17 of 68 cases the disease relapsed when therapy was tapered or discontinued. The relapse rate was 25%. The results indicated that CyA would be effective to the relapsed cases. The serum creatinine increased temporarily after administration of CyA in 5 cases, N-acetyl-beta-D-glucosaminidase (NAG) in 8 cases and eventually reached the normal range after the adjustment of dosage. The side effects included anorexia, nausea, vomiting and so on. CONCLUSION: CyA is one of the effective substitutes for the treatment of nephrotic syndrome, especially for the cases with MCNS and MsPGN. And CyA could control refractory nephrotic syndrome effectively and rapidly. The clinical effect was related to the blood concentration of CyA and pathological types.